Hydraulic surface treating process and equipment



P 29, 1964 E. UMBRICHT ETAL 3,150,467

HYDRAULIC SURFACE TREWIING PROCESS AND EQUIPMENT Filed Feb. 19, 1960! 2Sheets-Shani: l

INVENTQRS Emil Umbrich'r Willurd Lewis Johnson /zg /%/ms ,2 5 54mmATTORNEYS P 1964 E. UMBRICHT ETAL 3,150,467

HYDRAULIC SURFACE TREATING PROCESS AND EQUIPMENT Filed Feb. 19, 1960 2Sheets-Sheet 2 n 2 0/ ii a O O w 9 I O i o G E Fig 4 {NVENTORP EmllUmbrlchr Fig. 3 y Willard Lewis Johnson A TLTORNEYS United States Patent3,150,467 HYDRAULIC SURFACE TREATING PRGCESS AND EQUIPMENT EmilUmhricht, Northville, and Willard L. Johnson, Detroit, Mich, assignorsto Aiem Laboratories, Inc, Livonia, Mic-in, a corporation of MichiganFiled Feb. 19, 1960, Ser. No. 9,910 15 Claims. (Cl. 51-8) This inventionrelates to a process and apparatus for abrasive grinding, polishing,compacting, trimming or other surface altering of particles. Theinvention utilizes hydraulic means for imparting the required energy toabrasive or surface altering particles e.g., abrasive grains or blastinggrit or shot-peening, which are used in the invention. More particularlythe invention includes automatic reclamation and classification ofcleaned surface treating particles in the same equipment which is usedfor the abrading or peening or other surface altering of the articles.

There is a serious problem in thus altering the surface of materials,for example, for removing flash, sprue and other protrusions from castmetal or plastic articles, the removal of scale from heat treated metalarticles, the preparation of predetermined surfaces on metals byabrading or other compacting or polishing means and the altering ofsurfaces of metal articles by processes which reform the surface e.g.,by abrading away undesired surface material or altering molecular orcrystalline arrangements on the surface material. Typical of the lasttype of surface treatment is a shot peening process.

All of the operations referred to above require reforming of the surfaceof the article-Le, displacement and actual removal of portions of thearticle itself or such energetic treatment of the surface as to alterits crystal or molecular arrangements and/or other characteristics. Theprocedures have in common the requirement that solid particles whetherabrasive particles or peening particles must be supplied with a highdegree of energy so that they can reform the surface even in material ofconsiderable hardness and strength such as metals. Such surfacetreatment will be generally referred to as reforming.

One type of process for surface reforming which has been used for agreat many decades is exemplified by sand blasting. In early use of thismethod the high kinetic energy was imparted to the solid particles bycompressed air. This process is still used but presents seriousindustrial hazards when used in confined spaces and for the cleaning ofmetals.

The dust and fire hazards can be eliminated by use of a liquid streaminstead of an air stream; but attempts to utilize this commerciallyleaves much to be desired. The recovery of abrasive grains presentsproblems and the transport of the grains, e.g., through conduits issubject to clogging of relatively small passages and to abrasive damageto the equipment.

An entirely different problem is presented by the cleaning of bottlesand other articles the surface of which is not to be cut or otherwisereformed. In such cases very moderate speed jets of water have beenintroduced into or immediately below guide tubes communicating with thebottom of a hopper or tank containing water and the soft grains to actas scrubbers. In the case of bottle washing machines, for example, along tube extending up into the bottle projects a liquid streamentraining lead shot or rubber balls. A similar procedure has even beenused for the cleaning of automobiles, small pieces of rubber sponge orsimilar soft, easily deformable materials being used as the scrubbers.All of these require relatively large volumes of water, and etfect noreforming of the surface. These two problems have been separate andcompletely non-analogous. Wherever high Velocity surface reforminggrains have been involved, blasting by a gun technique has been used.

According to the present invention, very high speed jets of liquid canbe made to entrain and accelerate a liquid mass of suspended surfacereforming grains. For example, such grains can be settled in a carrierliquid in the bottom portion of a truncated conical hopper (or similarcontainer), and thus concentrated solids can be entrained into ablasting stream by ejector action of a high velocity jet directed into aguide tube (referred to in the claims as a conduit) which surrounds thehigh velocity stream to a level above the surface of liquid in thehopper. Thus the surface reforming grains can be projected from theguide tube in a fluid stream with high speed. The velocities used may bevaried to suit particular conditions and requirements but in general areso high that the surface-reforming grains carried therein acquire akinetic energy sufi'icient for the desired abrading or peening purposes.

There is advantage in use of very high velocities in the liquid blastingor shot peening. If the surface-reforming grains are merely entrained ina high velocity liquid, excess liquid may interfere with the optimumaction of the grains, but by using ultra high velocity ejector jets, itis possible to impart higher energy to the grains without excessivevolume of liquid. Throughout this specification and its claims this highenergy will be referred to as sufiiciently high to effect surfacereforming.

In the case of removing surface material, e.g., flash, sprue or otherundesired projections, or descaling or deburring, there is actualremoval of substantial portions of the material from the surfacetreated. In the case of peening processes the surface is reformed bychanging its surface micro-structure, although the reformation may besufficiently uniform that the change may not be apparent t the eye. Ofcourse, in some peening operations also there is actual removal, e.g.,knocking off, of portions of the treated surface such as brittle scaleor small protrusions. Thus, for example, the invention can perform adual function of descaling and peening. In other words, scale can beremoved and the remaining surface micro-structure changed by the sameoperation. In both cases the surface is being reformed in the sensereferred to above.

Not only has it been found practical to develop the high energy abradingor other surface reforming effects in equipment of the type described,but it is possible by using the present invention to have the equipmentperform a dual function. The hopper or container not only provides areservoir for the suspension of surface-reforming grains, but it alsocollects the drain-back material from the article being treated; and itcan serve also as a continuous hydraulic separator. By means of thisseparator, the excess of water, which is added by the high velocity jetsto impart the very high energy to the surface-reforming grains, isutilized for washing and hydraulic classifying of the recovered grainsand is then drawn off in quiescent condition carrying the more readilysuspended dirt, while the surface-reforming grains settle in the hopper.When the spent material returns into a hopper, it displaces excessliquid which continuously overflows, advantageously over the entireperiphery of the hopper.

The length of the overflowing edge may be increased to reduce thevelocity of flow, e.g., by use of a larger hopper. In other words thehopper behaves as a free settling classifier of particles in anhydraulic system.

Several types of solid material may be carried in the spent liquids. Forexample, the portion of the surface removed from the article beingtreated (e.g., scale, flash, sprue, burrs and the like) comes off asparticles which are sometimes considerably larger and sometimesconsiderably smaller than the blasting grains. Mold sand which hadadhered to castings, chip and filings on machined parts, ordinary dirtand oil, etc., may also be carried by the drain-off, and even thesurface-reforming grains may be worn or shattered into fine particles.Such fines, for the most part, have sufiiciently low settling rates sothat they are washed away into overflow from the hopper.

Effective cleaning by such hydraulic classification is an importantadvantage of the present invention. By settling clean grains, they canbe recycled for more surface reforming work, and still leave cleantreated articles.

The se aration of unwanted material from returned surface reforminggrains is all the more surprising because the throughput in the processof the present invention is high and relatively large amounts ofsurfacereforming grains pass through the apparatus in a short time.Nevertheless the present invention effects good efficiency in reuse ofthe surface-reforming grains and satisfactory cleaning thereof. Thereuse of these grains, moreover, subjects them to violent washing by theejector jets while they are being accelerated and entrained by theliquid. Any dirt which may have adhered to the grains is thus washedoff.

The nature of the surface-reforming grains used in the present inventiondepends substantially upon the result desired. When the surfacereforming desired is abrading, the ordinary abrasive grains may be usedsuch as, for example, sharp sand, grits of aluminum oxide, siliconcarbide, iron grit, malleable grit, steel grit, hard alloy grits, or thelike, or for more readily abraded surfaces, iron oxide grains. The reuseafter hydraulic classification also permits effective use of some of thematerial removed from the surface itself.

When peening is desired, the grains used according to the presentinvention, may be hard, tough shot, e.g., of iron or steel alloys in theform of small spheres or a round grain coarse sand such as sea sand; orworn sands no longer sharp enough for abrasive blasting. These may be,for example, silica or zircon sands. They should not be confused withsoft lead shot which have sometimes been used in bottle washing wherethe object is to prevent any possibility of surface alteration byabrasion, chipping or other reforming.

The shapes of the jets may vary. For small articles or articles withirregular surfaces round jets present many advantages. For otherpurposes, for example, descaling, peening or otherwise conditioning thesurfaces of large articles, flat metal sheets, etc., a jet mayadvantageously be in the form of an extended ribbon, preferably orientedacross the narrow dimension of the sheet or other article to be blasted,which can then be moved thereover. In the case of a wide ribbon jet thejet orifice, or nozzle, is, of course, of narrow more or lessrectangular shape. A similar effect can be produced with a series ofejector jets closely spaced side by side.

With round jets, greater uniformity can be obtained by using a guidetube with a cross-section smaller at the lower end where the high speedejector jet draws in the recycled grains and an enlargement at a higherlevel which enables the column of liquid to break free of friction withthe tube wall 5, etc. Guide tubes of uniform crosssection may be usedwith advantage in some cases; the invention is, of course, not limitedto guide tubes of varying cross-section but in a more specific aspectthe use of such expanded cross-section is to be regarded as a specificfeature of the invention.

It should be pointed out that the high effectiveness of the process andapparatus of the present invention is obtained without introducingsevere maintenance problems. The only portion of the apparatus which isexposed to high speed flow of the solid particles is the guide tube, andit is advantageously large enough so that such abrasive action is light.This tube may be made of highly abrasion-resistant materials, such asvery hard iron alloys or tough rubber, and can be made readilyreplaceable. This greatly reduces the cost and problem of maintenance,and permits obtaining the other advantages of the present inventionwithout offsetting economic disadvantages.

Water is the ordinary propelling liquid, but the invention will operatewith other liquids of suitable gravity and viscosity to impel, and laterto carry, the grains.

The jet of clear water or other non-abrasive liquid is combined with theabrasive material which is impelled thereby to high velocity in order todirect the resulting Wet blast against the desired parts of the surfaceto be treated.

The confining walls are, of course, subject to some abrasion; but, sincein practice of the present invention they need only be short tubes orequivalent inexpensive equipment, it is relatively unimportant that theymay eventually Wear out, as these parts subject to wear can, accordingto the present invention, be relatively cheap and designed forinexpensive replacement. Furthermore, wear in these parts can beminimized and in many cases almost completely eliminated by making theconduits with smooth continuous surfaces of a highly abrasion-resistantmaterial such for example as Meehanite, or with a lining ofabrasion-resistant rubber or similar elastomer. Such an elastomer liningcan be made to snap into the short conduit with flanges fitting over theends, so that replacement is only a matter of minutes. Even if wearoccurs in this part, the resultant change in dimensions would not becritical, so that the part can be used until it is worn through.

The invention will be described in greater detail in conjunction withthe drawings, in which FIG. 1 is a vertical section through the hopperportion of a simple apparatus for producing a round jet;

FIG. 2 is an isometric view, partly broken away, through an apparatusfor producing a ribbon stream or J FIG. 3 is a fragmentary detail inplan view of the bottom portion of the hopper of FIG. 2 showing adifferent nozzle form, and

FIG. 4 is a vertical section through a modified apparatus similar toFIG. 1.

In the apparatus of FIG. 1 the combined hopper and hydraulic purifier isshown as a container 1. The hopper is in the form of a truncated cone.In the bottom there is adjustably mounted a jet tube 2 held by a setscrew 3 and communicating with a pipe 4 from a source of clear waterunder high pressure. Above the jet tube 2 is a guide tube 5 which doesnot extend quite to the bottom of the hopper, but does extend above theliquid level. The liquid level is as shown in the hopper. The lowerportion contains most of the suspension of the settled surface-alteringgrains.

At a higher level the guide tube is shown of enlarged cross-section 6serving to hold back from the blast stream the liquid in the hopper,while releasing the stream from friction and the tube from abrasion. Thesmaller tube may be replaceable in the enlarged cup-like section, asshown, or the entire guide tube may be integral and replaceable as aunit.

The high velocity stream emerging from the tube 6 strikes an article(not shown) supported directly above it, the surface of which is to betreated.

After striking the article supported in the target zone, the spent blastliquid containing surface reforming grains and other materials carriedin the original blast, and/or resulting from the treatment, is kept fromscattering by a hood 7 and drains down into the hopper 1 causing anoverflow at the periphery. The peripheral edge of the hopper is madelevel so that the overflow uses substantially the entire length of saidedge, and a gutter 8, which collects the overflow, is sloped toward itsoutlet. The effluent may be run off to a settling basin or pond in whichany remaining abrasive is allowed to settle out before it is pumped.This overflow carries with it particles having lower settling rates,such as fines, low specific gravity particles and flaky particles, thesurface-reforming grains settle and are reused. Makeup grains, andchemical agents, if used, are introduced into the hopper as required.

FIGS. 2 and 3 show a modified apparatus in which the same parts bear thesame reference numerals. Instead of a single round jet tube 2 there iseither a narrow slot 2a, (see FIG. 2), or a series of round jet 2 sideby side, (see FIG. 3). The guide tube 5 is of circular cross section inFIG. 1, and of narrow rectangular section, as clearly illustrated inFIG. 2. It is positioned in the hopper by the spider 13.

The operation of the modified device .of FIGS. 2 and 3 produces a ribbonblast with the surface reforming-grains impelled to high velocity fortreatment of extended surfaces such as fiat sheets of metal or articleshaving broad surfaces which may be moved over the jet.

FIG. 4 illustrates another modification .of the basic apparatus shown inFIG. 1. Instead of returning all of the surface reforming particles tothe hopper and allowing them to sink to or near the bottom of the guidetube 5, where they are picked up again by the jet of liquid, only a partof the blasting grains is returned to the bottom of hopper 1b, and thereis provided a large supply pipe 12 entering the bottom of the hopperthrough an annular member 11. The jet pipe 2 is made coaxial with thesupply pipe 12 but extends beyond it in the bottom of the hopper 1b. Thepipe 12 communicates with a source producing a low velocity pump andmixer (not shown) whereby it feeds to the hopper a stream of asuspension of surface-reforming grains. Due to the low velocity of thisstream, there is little abrasion in pipe 12, but at the guide tube 5bthe high velocity ejector jet 2 accelerates the grains to the highenergy required for the desired surface-reforming. The operation on thearticle is as in FIG. 1; but a somewhat more precise control is madepossible. As shown only the most rapidly settling particles will berecycled through hopper 1b into the blast stream in 5b but it is alsofeasible to omit the hopper 1b and merely reduce the size of guide tube5b in the zone where the stream is accelerated by the jet 2, so that thehigh velocity can be attained in the blast stream with a low velocity inpipe 12.

FIG. 4 also illustrates the use of guide tube 5b of uniformcross-section and also the use of a snap-in lining 14 of abrasionresistant rubber or the like. This lining being held in place by its oWnresiliency is readily inserted and as readily stripped out and replacedwhen worn.

While it is an advantage that equipment of various sizes and designs maybe used in the present invention, for optimum results some of theproportions of the elements are of importance. Turning to FIG. 1 anddesignating the diameter of a jet tube 2 as D, the spacing of the guidetube 5 from the bottom of the hopper is advantageously in the range from1D to 20D, with the top of jet tube 2 advantageously well above thebottom point of the hopper, but advantageously below the guide tube byabout /2D to 20D. The diameter of guide tube 5 may vary from 2D to 4D.The length of the smaller (ejector) section .of tube 5 may be onlyenough to give the ejector action with the jet from tube 2, althoughgreater length is permissible. The cross-section of the enlarged portion6 is not critical, but it has the practical limit that it must not be solarge as to unduly reduce the settling area. It should be wide enough toassure freedom of the final jet emerging from the lower ejectorsections, and it must be high enough to be above the liquid level in thehopper so as to keep the liquid in the hopper away from the emergingjet.

In one specific example, the jet tube 2 may be a 1%" pipe nipple with awasher forming orifice 2' welded into its upper end, as shown in FIG. 1.The orifice is diameter. The guide tube 5 is 1 /2" outside diameter and1" bore and about 10" long and spaced about 2" above the bottom of thehopper 1 around the jet tube 2.

The enlarged tube portion 6 is about '5" diameter and extends upwardabout 10" above the top of the narrow guide tube 5 and about 1" abovethe liquid level in hopper 1. Tube 6 may terminate a little below theliquid level but one then has to depend on the jet action to clear thetube and hold back the blast. The liquid depth in the hopper is shownabout 20" and the width of the hopper is about 3', but wide variationsin size are permissible. In this particular example operated with 60psi. in the pipe 4, the velocity of the water leaving the orifice 2 atthe top of jet tube 2 was 4510 feet per minute and the velocity of theliquid blast leaving the top of tube 6 was 2510 feet per minute. ResultsWith these pressure and velocity conditions were very satisfactory, butit was found that increasing the jet velocity to two or three times ashigh increases the effectiveness especially for deburring and abradingoperations. In practical applications velocities have been used rangingfrom 2,200 to 11,300 feet per minute with pressures from 60 to p.s.i.;but the permissible range is much wider. The desired velocities dependso much on other factors including the nature of the base metal, whethersoft or hard, the extraneous surfaces to be removed in the deburringoperation, the size, hardness density and shape of the abrasiveparticles. For instance, with soft metal softer abrasive in finerpanticles might be desired to prepare a surface to the proper conditionwhile with hardened surfaces much larger abrasive particles with greatermass and/or abrading ability and generally harder characteristics areemployed. With these wide variations of conditions to be met as well asthe other operating factors, a wide range of velocities may be employed.It is believed that the velocities of liquid emerging from the jet tubesmay be selected within the range from 700 feet per minute to 100,00 feetper minute. Pressures in the jet pipe can be as high as 30,000 psi. orfor reforming some materials as low as 1 psi, but in practical use therange is advantageously kept below about 375 psi. With any specificpressure from the pump and orifice system, the velocities of liquidemerging from the blast tube may be high or small depending upon thesize of the blast tube and other accompanying conditions. In variousapplications of the hydraulic jet-impelled abrasive-suspended-in-liquidmethod velocities in the blast tube may be selected within the range 600feet per minute to 90,000 feet per minute to arrive at successfulconditions on specific abrading or deburring operations.

On a hard material such as cast iron or a fairly hard steel, goodconditions are found to be an orifice velocity of 11,000 feet perminute.

The dimensions set out above for FIG. 1 are applicable also to theribbon type spray apparatus of FIGS. 2 to 5 by considering D as thesmaller of the two dimensions of the slot 2a and similarly the diameterof the rectangular guide 2 as being the smaller of the two dimensions.The pressure at which liquid is supplied to the jet 2 drives it outthrough orifice 2' at such high velocity as to impart the necessarykinetic energy to the surfacereforming grains which flow into the guidetube 5. The ejector action of the jet 2 in the guide tube causes asubstantially solid stream of slurry of the surface-reforming grains tobe driven upward from tube 5 against the surface to be treated, and itspreads out only slightly (e.g., about 15) when it is freed from thetube 5.

It is advantageous to have the surface to be treated positioned in atarget zone quite close to the end of the guide tube, e.g., about 6" butit is not essential, so long as it is not so far away that the energy ofthe grains is seriously dissipated, e.g., in some cases 36" is foundsatisfactory. This greater distance of course may require greaterinitial velocity and/or a greater volume in the blast stream.

The relative volumes in the blast and in the settling hopper and thevelocity of the blast are adjusted so that a concentrated slurry of thesurface-reforming grains is maintained in the bottom of the hopper to alevel well above the bottom of guide tube e.g., to a depth of severalinches to a foot or more. To facilitate this for different operations,guide tube 5 may be adjustable vertically in clamp-bracket mounted onfixed supporting bars 16.

The above dimensions and velocities and pressures may be affected byother conditions, as will be clear to those skilled in this art. Thus,if the viscosity of the liquid used in the hopper 1 and the jet 2 ischanged, a change in the kinetic energy will follow. Thus acorresponding change in the liquid velocity may be made; and the abilityof the liquid to entrain the surface reforming grains can be controlledas required.

Change in the specific gravity of the liquidwhether by substitution of adifferent liquid or by additiveswill affect both the buoyancy (andconsequently the settling rates) of the grains in the liquid and thekinetic energy of the liquid blast when it strikes the surface beingtreated.

In most commercial installations more than one jet will be needed, andseveral of these can be included in the same tank (1, la, llb, etc.).The shape of the tank will depend in part upon the nature of the surfacebeing treated and the number of blast required. Ordinarily a slopingbottom as shown is advantageous to facilitate concentrating of a slurrynear the jet, but such concentration can be efiected in a supplementalapparatus or settling may be to a more or less flat bottom withmechanical scraper device to gather the settled solids.

The location of the orifice of jet tube 2 can be varied from below thebottom of tank 1 flush with the bottom, between the bottom and the lowerend of guide tube 5 and within the guide tube. The important point isthat it is located to give a maximum jet action, i.e., acceleration tothe surface-treating grains which pass through the guide tube 5 into theblast on the surface being treated.

Depending upon the efficiency of the jet action, a greater or lessamount of clear liquid has to be pumped into the jet, and an equalamount is drained out of the system. A certain amount of this isnecessary to wash out the dirt and broken down abrasive etc., and tomake up for inevitable losses of liquid but beyond that it isundesirable and I have found that good efficiencies are maintained withratios of about 0.65/1 to 1.5/1, or advantageously l/ 1 to 1.5/1,recycled slurry to fresh liquid in the jet.

From the foregoing, it will be apparent that the present inventionprovides a novel process for hydraulic surface treatment for abrasivecutting, trimming or surface altering of articles.

Although there is shown in the drawings and described above anembodiment of this invention and certain alternatives and indicatedranges of variation, it will be understood that these are not exhaustivebut are given rather to aid others skilled in the art in adapting andmodifying the invention so as to be best suited to the conditions andrequirements of each particular use.

We claim:

1. In apparatus for hydraulic blasting reforming of surfaces by surfacereforming impact with hard blasting grains hydraulically jet impelledagainst said surface with surface reforming velocity and kinetic energy,the combination which comprises a target area where said surfacereforming is to be effected, an open ended conduit spaced from saidtarget area and directed theretoward for conducting a hydraulic blastingjet stream to said target area, a container around said conduit andspaced adjacent one end thereof forming a reservoir for maintaining asupply of said hard blasting grains as a liquid slurry for admixture ina jet stream, high velocity and high pressure liquid jet means spacedfrom and O m directed into said conduit for providing a high velocityhigh pressure liquid jet through said supply of blasting grains in saidreservoir and into said conduit for entraining said blasting grains insaid jet and for impelling said grains through said conduit and againstsaid surface in said target area with said reforming velocity andkinetic energy for impinging on said surface to effect said reformingthereof, and means for supplying said liquid to said jet means at saidhigh pressure for providing said hydraulic blasting jet flow.

2. Apparatus as recited in claim 1 in which said container also extendsthroughout the transverse extent of said target area for providing acollection zone to receive liquid and blasting grains and materialactually removed from said surface after said hydraulic blastingthereof.

3. Apparatus as recited in claim 2 in which said container also includesmeans for effecting differential settling of said blasting grains andsaid removed material through said liquid therein for separating saidremoved material from said blasting grains and for returning saidseparated blasting grains to said supply thereof adjacent said conduit,and overflow means for withdrawing from said container a portion of saidliquid with said removed material suspended therein after said blastinggrains have settled therefrom.

4. An apparatus according to claim 1 in which the means for producing ahigh velocity jet are adapted to give the jet a ribbon shape, and theconfining conduit is of narrow rectangular cross-section whereby astream of suspended solids and liquid is produced in ribbon-like form.

5. An apparatus according to claim 4 in which the ribbon jet producingmeans includes a slit-shaped nozzle at the bottom of the container.

6. An apparatus according to claim 4 comprising means for introducing asuspension of surface-reforming solids in liquid at low velocity intothe bottom of the container adjacent the high velocity liquid jetproducing means.

7. An apparatus according to claim 4 in which the ribbon jet producingmeans includes a plurality of circular nozzles side by side in thebottom of the container.

8. An apparatus according to claim 1 in which the conduit is providedwith an abrasion resisting inner surface.

9. An apparatus according to claim 1 comprising means for introducing asuspension of surface-reforming solids in liquid at low velocity intothe bottom of the container adjacent the high velocity liquid jetproducing means.

10. In a method for hydraulic blasting surface treatment of castings andmolded articles and the like for reforming the surface thereof bydisplacement and actual removal or altering the molecular structure ofsurface portions of the article by surface reforming impact with hardblasting grains hydraulically jet impelled against said surface of saidarticle at a surface reforming velocity and kinetic energy, the stepswhich comprise positioning said article in a target zone for saidhydraulic blasting and with the surface of said article to be reformeddisposed to receive said blasting, forming a high velocity and highpressure liquid jet at a jet source spaced from said target zone andwith said jet directed toward said target zone, and with said jetconfined within an open-ended conduit spaced from both said jet and saidtarget zone, maintaining as a reservoir adjacent said jet source aquantity of said blasting grains as a liquid slurry for said hydraulicblasting, directing said liquid jet through said reservoir of blastinggrains for entraining in said liquid jet blasting grains from saidreservoir thereof for impelling toward said surface of said article insaid target area, impelling said grains against said surface to bereformed at a reforming velocity and pressure and kinetic energy, andeffecting said reforming of said surface of said article by impact ofsaid jet-impelled grains against said surface.

11. The method of hydraulic blasting surface reforming as recited inclaim 10 in which the velocity of said high velocity liquid jet is atleast about 700 feet per minute for imparting to said impelled grainskinetic energy for said reforming.

12. The method of hydraulic blasting surface reforming as recited inclaim 10 in which said article being reformed is metal and in which thepressure of said high pressure liquid jet is within the range of about60 to 120 p.s.i. for imparting to said impelled grains kinetic energyfor said reforming.

13. The method of hydraulic blasting surface reforming as recited inclaim 10 in which the velocity of said high velocity liquid jet is atleast about 2200 to 11,300 feet per minute for imparting to saidimpelled grains kinetic energy for said reforming.

14. The method of hydraulic blasting surface reforming as recited inclaim 10 in which said entraining and impelling jet liquid is watersupplied at a substantial high pressure up to about 375 p.s.i.

15. The method of hydraulic blasting surface reforming as recited inclaim 10 which also includes steps of collecting said blasting grainsand material actually removed from said surface of said article admixedwith said liquid in a collection zone after said impelling against saidarticle, separating and withdrawing from said collection zone saidmaterial removed from said surface of said article, and returning saidblasting grains from said collection zone to said reservoir of blastinggrains adjacent said liquid jet source for subsequent impelling againstsaid surface to be reformed.

References Cited in the file of this patent UNITED STATES PATENTS252,979 Tilghman Jan. 1, 1882 356,598 Moore Jan. 25, 1887 513,502 GrunigJan. 30, 1894 624,097 Robb May 2, 1899 805,029 Reichhelm Nov. 21, 1905990,409 Walsh Apr. 25, 1911 1,040,477 Weiscopf Oct. 8, 1912 2,200,587Tirrell May 14, 1940 2,600,358 Bolton et a1 June 10, 1952 2,605,596 UhriAug. 5, 1952 2,858,653 Guptill Nov. 4, 1958 2,985,050 Schwacha May 23,1961 FOREIGN PATENTS 789,513 Great Britain Jan. 22, 1958

1. IN APPARATUS FOR HYDRAULIC BLASTING "REFORMING" OF SURFACES BYSURFACE REFORMING IMPACT WITH HARD BLASTING GRAINS HYDRAULICALLY JETIMPELLED AGAINST SAID SURFACE WITH SURFACE REFORMING VELOCITY ANDKINETIC ENERGY, THE COMBINATION WHICH COMPRISES A TARGET AREA WHERE SAIDSURFACE REFORMING IS TO BE EFFECTED, AN OPEN ENDED CONDUIT SPACED FROMSAID TARGET AREA AND DIRECTED THERETOWARD FOR CONDUCTING A HYDRAULICBLASTING JET STREAM TO SAID TARGET AREA, A CONTAINER AROUND SAID CONDUITAND SPACED ADJACENT ONE END THEREOF FORMING A RESERVOIR FOR MAINTAININGA SUPPLY OF SAID HARD BLASTING GRAINS AS A LIQUID SLURRY FOR ADMIXTUREIN A JET STREAM, HIGH VELOCITY AND HIGH PRESSURE LIQUID JET MEANS SPACEDFROM AND DIRECTED INTO SAID CONDUIT FOR PROVIDING A HIGH VELOCITY HIGHPRESSURE LIQUID JET THROUGH SAID SUPPLY OF BLASTING GRAINS IN SAIDRESERVOIR AND INTO SAID CONDUIT FOR ENTRAINING SAID BLASTING GRAINS INSAID JET AND FOR IMPELLING SAID GRAINS THROUGH SAID CONDUIT AND AGAINSTSAID SURFACE IN SAID TARGET AREA WITH SAID REFORMING VELOCITY ANDKINETIC ENERGY FOR IMPINGING ON SAID SURFACE TO EFFECT SAID REFORMINGTHEREOF, AND MEANS FOR SUPPLYING SAID LIQUID TO SAID JET MEANS AT SAIDHIGH PRESSURE FOR PROVIDING SAID HYDRAULIC BLASTING JET FLOW.